This is an extract of our Medicine & Surgery document, which we sell as part of our Medicine and Surgery Notes collection written by the top tier of Bristol University students.
The following is a more accessble plain text extract of the PDF sample above, taken from our Medicine and Surgery Notes. Due to the challenges of extracting text from PDFs, it will have odd formatting:
Medicine & Surgery Cardiology Essential anatomy
? Sinus node o Generates impulses automatically by spontaneous depolarisation of its membrane o Pacemaker o Influx of sodium controls the depolarisation
o The rate of depolarisation is controlled by: autonomic tone, stretch, temp, hypoxia, pH
? Atrial & ventricular myocyte action potentials o Different to sinus node cells o Arrival of AP opens Na channels resulting in a fast depolarisation Cardiac Cycle
Cardiac arrhythmias Bradycardia<60bpm Tachycardia>100bpm
Mechanisms of arrhythmia production Sinus bradycardia - slow automacity Bradycadia due to AV block - abnormal conduction in the AV node
? Accelerated automacity o Reducing the threshold potential o Increasing the rate of diastolic depolarization
? Triggered activity o Myocardial damage can lead to oscillations in the transmembrane potential o These 'after depolarisations' may reach the threshold and produce an arrhythmia
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